Purple Rinse Water

[Paul73]

I am a newbie to this process and I am not sure what happened. I have a few ram fingers that were recovered using the AP process. I filtered the liquid to recover the fingers and noticed that my distilled water that I used to rinse was turning a light purple color. Everything I can find in the forum conversations and dong a word search in the Hokes book related to the color change mentioned using Stannous Chloride to test for gold and getting the purple color. My containers and final filters (cotton ball filters) were clean to the best of my knowledge, the initial finger recovery was done using paper towels as the filter. The recovered fingers were stored in a plastic prescription bottle that I had cleaned prior to using it. Nothing in this part of the process had been exposed to any Stannous Chloride. I am at a loss to explain it and cannot seem to find any explanation for it. I know there is some copper contamination because I started to do the AR process to dissolve the gold and what was initially a golden colored solution turned a light shade of green. I realize this is just the rinse water I am describing but I am wondering what effect it may cause as I get further into the refining and melting portion of the process. Sorry for being so long winded but I am trying to describe what is happening as best as I can. Anybody else ever run into this?

 

[4metals]

Was there any solder on the fingers you dissolved? If there was it’s possible you formed some tin chloride which reacted with the gold to form a colloid of elemental gold supported on tin dioxide to give a purple precipitate or coloration.

Colloidal gold is difficult to filter and often stays suspended in the solution imparting a purple color.

 

[butcher]

Tin (solder) if involved in the leaching process of the gold foils, tin will dissolve into the cupric chloride leach solution (what you are referring to as AP solution), making stannous chloride as one of the metal chloride salts dissolved in this solution of mainly copper chlorides.

If you use the excess oxidizer in the cupric chloride leach (AP), such as too much H2O2 (generating chlorine strong enough to put some gold into the solution) some of the gold can dissolve, and most of the time the undissolved copper will displace this gold (cement it back out of the solution) as black powder, but if tin from solder is dissolved in this solution with gold ions (a dissolved chloride salt of gold in a mixture of the dissolved chloride salt of tin, the gold will be reduced to metal but will be locked up in suspension in this solution as a colloidal gold (purple of Cassius) that the gold atoms will not combine or settle without breaking the colloid.

 

[orvi]

This happened also to me. Twice. Once, I was processing full plated boards (cut down to smaller pieces), second time fingers.
In the first batch, there were several holes in the PCBs, where the tin/remains of the leg didn´t fully dissolved. When I removed the boards and start rinsing them, rinse water slowly get violet tinge.
Next time I was processing fingers, where all of the metallics dissolved into the AR. But this time, violet colour persisted in washings even if all metals have passed to the solution.

One thing which we should be aware of is, that cuttings from boards and fiberglass PCBs in general tend to adsorb appreciable ammount of gold into them. When the boards were removed from the juice, and rinsed, Au3+ slowly started to leak out from the surface of them, getting into the contact with few tin/legs remains and violet colour was created.

Second, there are some resins, espetially fenol/formaldehyde types, that have functional groups capable of reducing gold. This was the second case with fingers - they were capable of making gold colloids by themselves.

Important to add here, AR isn´t very good way how to process fingers. Nitric or AP are much better approaches. In my cases, there was significant ammount of tin covered board that was obviously plated before. Nitric will produce ultrafine gold dust, and unfortunately I cannot run AP in my place (various reasons).

 

[Paul73]

Thanks all for your replies. After reading them, I believe I did use too much oxidizer, these fingers were recovered using white vinegar and hydrogen peroxide and being a newbie to this process I became impatient and apparently used to much peroxide attempting to speed up the process. There were a few small pieces of circuit boards in the AP soak. I placed them in because they were showing what I thought were small spots of gold. I did a stannous test on the rinse liquid and did not see any apparent test results but my understanding of the test now that I give it some thought would not show results from suspended particles as it will only test for the gold to be in solution and on top of that a slight indication would be hard to see due to the purple initial color of the water. The Stannous test on the liquid I saved was a very deep purple color which is a good result. I am going to let the rinse water set for a few days and see what if anything settles. Then depending on the results decide that to do with the rinse waters. I was attempting the AR process to increase the gold purity. This was my second attempt at recovery. The first attempt resulted in about .5g of gold that tested at about 12 karat after melting it (I am estimating this result).
Any thoughts on a good way to process the rinse waters to enhance the recovery of whatever is suspended in it?

 

[butcher]

Gold particles in the purple solution will never settle on their own, each tiny cluster of atoms of gold becomes electrically charged (which stops them from coming into contact with each other to settle with gravity in solution, and like floating magnets these clusters repel each other, and so are held in suspension and in motion by their own force of electrical charge.

The colloid will not break on its own, your gold can be locked up in solution until the chemical reaction to break the colloid is forced upon it.

Strong acid like sulfuric acid and heat can break the electrical charge on the gold particles or the colloid so that the gold atoms can come together in contact with each other and grow to larger clusters (as powder) and settle out of the solution, another option to break the colloid is to use electrolysis.

 

[dpgold]

Thanks all for your replies. After reading them, I believe I did use too much oxidizer, these fingers were recovered using white vinegar and hydrogen peroxide and being a newbie to this process I became impatient and apparently used to much peroxide attempting to speed up the process. There were a few small pieces of circuit boards in the AP soak. I placed them in because they were showing what I thought were small spots of gold. I did a stannous test on the rinse liquid and did not see any apparent test results but my understanding of the test now that I give it some thought would not show results from suspended particles as it will only test for the gold to be in solution and on top of that a slight indication would be hard to see due to the purple initial color of the water. The Stannous test on the liquid I saved was a very deep purple color which is a good result. I am going to let the rinse water set for a few days and see what if anything settles. Then depending on the results decide that to do with the rinse waters. I was attempting the AR process to increase the gold purity. This was my second attempt at recovery. The first attempt resulted in about .5g of gold that tested at about 12 karat after melting it (I am estimating this result).
Any thoughts on a good way to process the rinse waters to enhance the recovery of whatever is suspended in it?

It happen to me too, I did AP on a batch of mylar ribbon contacts and I could see extremely fine gold sparkling in the solution. I have filtered and I got.....0.5 yield on a little over 2kg of material. I kept the AP for reuse and stockpot and I might have save more from it already. Initially I htought the gold could be either in the solution or in the precipitate but it seems like this is a third state of gold this is why it is identified as this. If you look up colloidal gold you will find lots of interesting stuff. If the solution is somewhat clear you can see if there is colloidal gold by putting a laser through a beaker and watching from above. If it is colloidal gold you could see the laser path as a line.

 

[Paul73]

It happen to me too, I did AP on a batch of mylar ribbon contacts and I could see extremely fine gold sparkling in the solution. I have filtered and I got.....0.5 yield on a little over 2kg of material. I kept the AP for reuse and stockpot and I might have save more from it already. Initially I htought the gold could be either in the solution or in the precipitate but it seems like this is a third state of gold this is why it is identified as this. If you look up colloidal gold you will find lots of interesting stuff. If the solution is somewhat clear you can see if there is colloidal gold by putting a laser through a beaker and watching from above. If it is colloidal gold you could see the laser path as a line.

I removed the filters that were in this liquid and tried to rinse the color out of them. They remained purple, so I took them out of the funnel and squeezed the remaining liquid out of them. I then decided to incinerate them to see what took place and as I incinerated I could see tiny gold beads forming. Unfortunately my melt dish was very dirty so they are going to be hard to recover. I think I will try cleaning the melt dish and try something (not sure what yet) to see if I can separate them from whatever comes out of the dish.
I could see tiny particles floating in the liquid. I tried a laser pointer as you described in your reply and it did show a laser light path very plainly visible. I decided to evaporate some of the liquid just to see what would happen. I let it on a coffee warmer overnight and evaporated about 1/2 the liquid level. The purple color remained, and there is a layer of cloudy purple sediment at the bottom that is not entirely settled as it is still very fluid and seems to be floating slightly above the bottom of the vessel. Very interesting stuff.
I am reading the Hokes book about the melting of precious metals and learning a lot as I go. But being the impatient person I am I am experimenting as I go and following up with the reading. Bad way to go I know but that is me, stubborn, bullheaded, and impatient.

 

[Paul73]

Gold particles in the purple solution will never settle on their own, each tiny cluster of atoms of gold becomes electrically charged (which stops them from coming into contact with each other to settle with gravity in solution, and like floating magnets these clusters repel each other, and so are held in suspension and in motion by their own force of electrical charge.

The colloid will not break on its own, your gold can be locked up in solution until the chemical reaction to break the colloid is forced upon it.

Strong acid like sulfuric acid and heat can break the electrical charge on the gold particles or the colloid so that the gold atoms can come together in contact with each other and grow to larger clusters (as powder) and settle out of the solution, another option to break the colloid is to use electrolysis.

I do not have an electrolysis setup yet. I am in the process of building one, but being on a fixed income it is slow going. I do have some sulfuric acid and I am thinking about adding some to the rinse water just to see what happens. The liquid I have is a very small amount and I am wondering what would be the best way to do the addition. At this time I am thinking of adding it a drop at a time and giving some time between each addition to see what the reaction is. Currently I have evaporated about 1/2 the liquid level on low heat and am noticing a purple scum floating slightly above the bottom of the jar. I am also thinking I may just split the liquid up and evaporate 1//2 the liquid completely to see what would remain and trying the sulfuric acid on the other half. Will post the results after the experiment.

 

[Shark]

I am reading the Hokes book about the melting of precious metals and learning a lot as I go. But being the impatient person I am I am experimenting as I go and following up with the reading. Bad way to go I know but that is me, stubborn, bullheaded, and impatient.

As a suggestion, try reading first, then experiment. This way you can see how the things you read work.

 

[Martijn]

How many RAM fingers are we talking here?

White Vinegar + H2O2 is not AP. Did you use iodized salt for that experiment to create weak HCl?

Currently I have evaporated about 1/2 the liquid level on low heat and am noticing a purple scum floating slightly above the bottom of the jar. I am also thinking I may just split the liquid up and evaporate 1//2 the liquid completely to see what would remain and trying the sulfuric acid on the other half. Will post the results after the experiment.

So it does settle, just needs some time and heat.
Separate an evaporate, great idea, give it a try. Add a dash of H2SO4, you might be done earlier than you expect.

Knowing you're stubborn is half the work done, The other epiphany half is written here: please read it completely!!
Try to feel the severity of the near death experiences, very unexpected effects of fumes and reactions these members try to warn us for.

https://goldrefiningforum.com/threa...imple-question-and-get-a-simple-answer.21412/
This is chemistry! Not play dough.
Be safe, stay alive.

Martijn.

 

[Paul73]

Gold particles in the purple solution will never settle on their own, each tiny cluster of atoms of gold becomes electrically charged (which stops them from coming into contact with each other to settle with gravity in solution, and like floating magnets these clusters repel each other, and so are held in suspension and in motion by their own force of electrical charge.

The colloid will not break on its own, your gold can be locked up in solution until the chemical reaction to break the colloid is forced upon it.

Strong acid like sulfuric acid and heat can break the electrical charge on the gold particles or the colloid so that the gold atoms can come together in contact with each other and grow to larger clusters (as powder) and settle out of the solution, another option to break the colloid is to use electrolysis.

Something odd is going on then because I have started to see small pieces of gold in the solution and left alone the water became clear and the purple has settled to the bottom of the jar. This happened like overnight and no additional chemicals have been added. The evaporation process was speeded up by heat, (not a lot of heat did not boil) the heat was supplied by an electrical coffee warmer like you would place next to your armchair to keep your coffee warm. So there are very small gold pieces in this solution and still the purple color. Still reading Hokes book and searching the forum for the two handbooks mentioned in a post. Found a link posted in a signature line but when I searched it the forum came back with an error message that it could not be found!

 

[Paul73]

How many RAM fingers are we talking here?

White Vinegar + H2O2 is not AP. Did you use iodized salt for that experiment to create weak HCl?


So it does settle, just needs some time and heat.
Separate an evaporate, great idea, give it a try. Add a dash of H2SO4, you might be done earlier than you expect.

Knowing you're stubborn is half the work done, The other epiphany half is written here: please read it completely!!
Try to feel the severity of the near death experiences, very unexpected effects of fumes and reactions these members try to warn us for.

https://goldrefiningforum.com/threa...imple-question-and-get-a-simple-answer.21412/
This is chemistry! Not play dough.
Be safe, stay alive.

Martijn.

Yes I did use salt to make a weak HCL. However it was not iodized salt it was a sea salt as that is what was recommended for the process. I am staying as safe as I can. All processes are being done outside in a covered deck I built several years ago to accommodate our hot tub, it only has two walls and the floor has large open cracks where the green lumber that was used has shrunk. I have read through the thread you mentioned and understand and agree with it but stull questions remain and will be asked from time to time. The learning experience goes on and on forever. I definitely will be trying a dash (drops at a time) of H2SO4.

 

[Alondro]

This happened also to me. Twice. Once, I was processing full plated boards (cut down to smaller pieces), second time fingers.
In the first batch, there were several holes in the PCBs, where the tin/remains of the leg didn´t fully dissolved. When I removed the boards and start rinsing them, rinse water slowly get violet tinge.
Next time I was processing fingers, where all of the metallics dissolved into the AR. But this time, violet colour persisted in washings even if all metals have passed to the solution.

One thing which we should be aware of is, that cuttings from boards and fiberglass PCBs in general tend to adsorb appreciable ammount of gold into them. When the boards were removed from the juice, and rinsed, Au3+ slowly started to leak out from the surface of them, getting into the contact with few tin/legs remains and violet colour was created.

Second, there are some resins, espetially fenol/formaldehyde types, that have functional groups capable of reducing gold. This was the second case with fingers - they were capable of making gold colloids by themselves.

Important to add here, AR isn´t very good way how to process fingers. Nitric or AP are much better approaches. In my cases, there was significant ammount of tin covered board that was obviously plated before. Nitric will produce ultrafine gold dust, and unfortunately I cannot run AP in my place (various reasons).

I take care of that by soaking my trimmings in pure HCl for a solid week, shaking and stirring daily, alternating heating and cooling repeatedly.

It takes longer, but ALL the base metals are utterly gone by the time it's done. Then, after the gold dissolve, I boil the solids left over in distilled water to remove all hidden dissolved gold chloride in the board bits.

Thanks to Sreetips for showing such detailed wash methods to make sure all the values are recovered!

 

[Paul73]

Hello Alondro, how did you dissolve your gold? My understanding is that it will not dissolve in straight HCL. I did not know about boiling the leftover solids, I will have to look into that. I just started recovering and am learning a lot. I printed out a copy of Hokes book and am studying it now as I go. I know, and have been reminded many times to read it first but with what is going on I have a limited time to get done what I want to do before travelling south again and will not be able to take my hobby with me.

 

[Hartbar]

Hokes book is incredible. I’ve read it a few times now.
I just don’t see how it applies to the modern E/ waste stuff people are processing to be honest.
If you read it straight up, it’s a reference for jewelers in the 1950’s to 70’s. Most of the info still relevant today for jewelers.

 

[Paul73]

I am getting some information that kind of relates so far as far as equipment and some setup stuff but I am only up to chapter VI so far.

 

[Paul73]

Yes I did use salt to make a weak HCL. However it was not iodized salt it was a sea salt as that is what was recommended for the process. I am staying as safe as I can. All processes are being done outside in a covered deck I built several years ago to accommodate our hot tub, it only has two walls and the floor has large open cracks where the green lumber that was used has shrunk. I have read through the thread you mentioned and understand and agree with it but stull questions remain and will be asked from time to time. The learning experience goes on and on forever. I definitely will be trying a dash (drops at a time) of H2SO4.

Interesting that I have split the wash waters up and have two samples that both weigh the same. I have not evaporated yet but am noticing small flecks of gold in both samples. The purple has settled to the bottom but when swirled around is still purple. I am seeing about the same amount of gold specs in each sample. Have added H2SO4 to one of them and do not see an appreciable change. Both samples weigh 45g and counting the drops I have added about 10 drops also my droppers (pipettes) got here today so in addition to the 10 drops I have added 2ml of H2SO4 to the one I am treating. It has been several hours and still no appreciable change noticed. We will see in the morning if anything has developed.

 

[dpgold]

Hokes book is incredible. I’ve read it a few times now.
I just don’t see how it applies to the modern E/ waste stuff people are processing to be honest.
If you read it straight up, it’s a reference for jewelers in the 1950’s to 70’s. Most of the info still relevant today for jewelers.

the basic reactions and reactants are the mostly the same in the book, I am not sure it covers everything and for a beginner some things should be explained further. Also the books calls for acquaintance tests. I think the book, being old, does not cover the safety issues very well, it does not explain the safety issues very well, maybe mentions them. There are dangerous gases and chemical reactions which transform some plain substance into a lethal stuff which a beginner would never fully understand and know how to handle. Like there are off gases which are dangerous and then some salts which are off the charts dangerous. The unsuspecting person at home, in the beginning, might try some of these in the kitchen thinking they would wash things up and everything is fine. Then there are many misleading youtube videos where everything seem possible.

 

[butcher]

If you are seeing a violet salt settle it is not colloidal gold, it is more likely a diluted solution with silver chloride that has been reduced by exposure to light.

Colloids are too small to be able to see them physically without a special microscope as the clusters of gold atoms are too small, we may detect them by the reflection of light through a sloution giving color to the solution (not a salt), it can also be detected by how the is light reflected or scattered through the solutionTyndall effect.

silver chloride will form a milky white in solution, which will make a fluffy white salt that will seem to float around, as the other salts are normally heavier or denser as they settle faster than the silver chloride will.
If the solution is dilute or low of free acid the silver chloride if exposed to light will begin to turn violet to blackish on the surface of the salt as the surface layer of the silver chloride is being reduced to silver metal.